Exploration and production of petroleum, including oil and gas require the use of drilling rigs to drill wells deep in subterranean formations. These wells are expensive to both drill and operate. Advancements in technology have permitted deeper wells, which in turn have resulted in a need to have drill floors be higher above the ground in order to accommodate larger and more complex equipment, such as blow-out preventers (BOPs) with more cavities and rotating BOPs.
A typical operating drilling rig includes a substructure, a drill floor, and a vertical mast with a crown mounted thereon. The mast typically has a traveling block reeved with wire rope from a drawworks to the crown, enabling the traveling block to be raised and lowered. A top drive is connected to the block for drilling the well. The drill floor typically includes the drawworks, an automated roughneck, and a rotary table with a bowl to accept manual or automated slips for the securing and holding of tubulars.
In order to accommodate the need for an elevated drill floor, numerous structures and raising systems have evolved, but each has proven deficiencies. For example, conventional systems have utilized drawworks, hydraulic cylinders, and/or winches to raise the mast and drill floor. However, those structures requiring the use of the drawworks for the raising of the mast must wait until all loads of the rig have been moved and its supporting generators, SCR/drives and control system are operational. Accordingly, the drill site must be substantially set up even before the mast can be raised. This delay is extremely expensive and requires the rig operating footprint to be great enough to accommodate the un-erected substructure, mast (in horizontal position) and all its loads.
Some prior mast raising systems utilize a plurality of hydraulic cylinders that lift the mast from a horizontal position to a vertical position. However, these are very large, are very expensive, and risk hydraulic failure or uneven extension which can introduce some level of torque to the mast that may cause damage. In addition, these types of hydraulic cylinders require intensive maintenance programs. Hydraulic cylinders with counterbalance valves to prevent the uncontrolled retracting of the cylinders are still susceptible to seal failures. A seal failure often results in damage to the mast and/or substructure.
The present disclosure is directed to overcoming one or more of the deficiencies of the prior art.